In reversed-phase HPLC, a nonpolar stationary phase (typically silica or polymer-based with hydrophobic functionalities) and a polar mobile phase (aqueous or organic solvent) are employed. Nonpolar analytes elute faster, while polar analytes elute later. This mode is widely used for separating small organic molecules, pharmaceutical compounds, and hydrophobic biomolecules.

Normal-phase HPLC employs a polar stationary phase (silica or other polar media) and a nonpolar mobile phase (organic solvents). Polar analytes elute faster due to stronger interactions with the stationary phase. This technique is effective for separating highly polar compounds, such as sugars, organic acids, and some natural products.

Ion-exchange HPLC uses a stationary phase with ionizable groups, such as positively or negatively charged resins. The analytes are separated based on their charge properties, with oppositely charged analytes attracted to the oppositely charged stationary phase. This technique is employed for analysing charged biomolecules, such as proteins, peptides, and nucleic acids.

Also known as gel filtration chromatography, SEC separates analytes based on their size or molecular weight. It employs a porous stationary phase that allows smaller molecules to enter the pores, resulting in their longer retention time, while larger molecules pass through the column more quickly. SEC is commonly used for separating biomolecules, polymers, and nanoparticles.

Affinity chromatography utilizes specific interactions between a target analyte and a ligand immobilized on the stationary phase. It provides highly selective separations, allowing the isolation and purification of specific biomolecules, such as antibodies, enzymes, and receptors. The stationary phase can be tailored to interact with the target molecule, enabling efficient separation and purification.

HPLC plays a vital role in pharmaceutical analysis, providing accurate and reliable data for drug development, quality control, and formulation. It enables the separation, identification, and quantification of drug compounds and impurities. HPLC techniques such as reversed-phase chromatography, size-exclusion chromatography, and ion-exchange chromatography are employed to analyse drug purity, stability, dissolution, and bioavailability.

HPLC is extensively used in environmental analysis to detect and quantify pollutants, pesticides, herbicides, and contaminants in various matrices such as soil, water, air, and food. It helps assess environmental impact, monitor compliance with regulatory standards, and evaluate the efficiency of remediation processes. HPLC techniques like reversed-phase, normal-phase, and ion-exchange chromatography aid in analysing complex environmental samples.

HPLC is applied in the food and beverage industry for quality control, authenticity testing, and analysis of additives, contaminants, vitamins, flavours, and preservatives. It helps ensure compliance with food safety regulations and verifies product labeling claims. HPLC techniques like reversed-phase and ion-exchange chromatography are utilized to analyse food and beverage samples accurately.

HPLC is indispensable in forensic laboratories for analysing drugs, toxicology screening, identification of controlled substances, and measuring blood alcohol levels. It provides accurate identification and quantification of drugs and metabolites in biological samples. HPLC techniques such as reversed-phase chromatography, solid-phase extraction, and chiral chromatography are employed for forensic analysis.

HPLC is utilized in the chemical industry for analysing and characterizing chemical compounds, polymers, and intermediates. It aids in quality control, process optimization, and identification of impurities or reaction by-products. HPLC techniques like reversed-phase, normal-phase, and size-exclusion chromatography are commonly employed in chemical analysis.

HPLC is widely used in biotechnology and life sciences research for analysing biomolecules such as proteins, peptides, nucleic acids, carbohydrates, and metabolites. It helps in protein purification, characterization, and quantification. HPLC techniques like reversed-phase, ion-exchange, and size-exclusion chromatography are employed for biomolecule analysis.

HPLC is employed in the analysis of cosmetic ingredients, preservatives, fragrances, and active compounds in personal care products. It ensures product safety, quality, and compliance with regulatory requirements. HPLC techniques like reversed-phase and normal-phase chromatography are utilized for cosmetic analysis.